on one side without interfering with the other. This is a mistake, as of course it often occurs that the books on one side of a case are taller or shorter than those on the other, and so inconvenience and waste of space will frequently happen. In all double bookcases each shelf should have a separate bracket, rack, or pin arrangement for altering its height, independent of its fellow on the other side. The bookcases at Halle are eight divisions in width, and each division is 1 metre wide. The staircase in the centre of the book stack takes up 2 metres, the total width of the stack being about 20 metres. The floors are of perforated iron-work, and are arranged to fall opposite the centre of the windows, so that each storey has light from about 1½ square metres of window.
In Fig. 16 is given a section of half of the book stack in the University Library at Greifswald. It will be seen that two storeys of the stack are below the floor level of the reading-room, and four above. Light is obtained from a skylight in the roof and from large side windows, each of them being planned to light two storeys of the stack, the stone-work of the outer walls being placed opposite the floors. The cases vary a little in height, the five top storeys being 2½ metres, and the bottom one 2⅓. There is also a basement, 2 metres in depth, underneath the book store, to provide against the possibility of any damp arising from the ground and damaging the books. The cases are divided into five divisions, each a metre
